1. Field of the Invention
The present invention relates in general to the recovery of hydrocarbons from underground geologic host formations and particularly relates to the sequential extraction of hydrocarbons from such formations using a series of artificial aquifers.
2. Description of Prior Developments
Hydrologic cells for recovery of hydrocarbons and thermal energy from carbonaceous formations have been described in U.S. patent application Ser. No. 08/852,327 and Ser. No. 09/041,503. Such cells increase the sweeping efficiency of oil recovery by fluid injection, and can recover hydrocarbons from heavy-oil reservoirs, tar sands and gas hydrates by steam-flooding, through the installation of artificial aquifers so that an injected fluid can be driven under a pressure differential from a source aquifer or injection well to a sink aquifer or producing well. The source and sink aquifers are formed by hydrofracturing between two wells. This invention proposes a different approach to the problem of making a long continuous fracture surface through a combination of the available techniques of drilling and hydro-fracturing.